Arguably a perspective here is not that the JVM is more successful but that simply that Java as a language is less successful/more deficient language than C# an

Arguably a perspective here is not that the JVM is more successful but that simply that Java as a language is less successful/more deficient language than C# and leaves more evolutionary niches available for other languages to coexist in its ecosystem, whereas C# checks more boxes generally. One reading of the history of Kotlin is that is almost directly the reason for Kotlin's existence in the first place because Java itself fell so far behind C# state of the art. The DLR made it much easier for dynamic languages on .NET to interact and share infrastructure on top of the CLR, but it also gave C# directly just enough dynamic language powers that filled most people's use cases for that niche. Even in the current race between C# and F#, unless you are using features such as Units of Measure or Type Providers, there is often a sense of "you don't need to use F# because that feature will be eventually in C# anyway" and "F# is just a proving ground for C# ideas". The F# community continues to try to find marketing messages that aren't that and better highlight some of the niches that F# can fill that C# won't. The most recent attempts have been trying to position F# as a "data sciences" language useful for Notebook-driven development in direct comparison/competition to Python/R/Julia. C# actually is finally useful in Notebooks now and has some alright REPL support, but F# likely will always better fit that niche. It will be interesting to see if that marketing approach helps.